#!/usr/bin/env ruby

# Wrag stands for writeable-ag; a hacky script that allows you to search with ag
# <https://github.com/ggreer/the_silver_searcher> and edit the results in
# $EDITOR. The changes are propagated to all listed files, if any.
#
# Usage: wrag [pattern]
#
# TODO Also rename changed filenames
# TODO Assemble sed string to make this atomic

require 'optparse'
require 'tempfile'
require 'shellwords'

def usage
  puts "Usage: #{File.basename($0)} [-f|--rename-files] [-b|--backup] search_string"
  puts "\nAny of ag's flags will work with wrag"
  exit
end

usage if ARGV.empty?

## Parsing options ################################
options = {:rename => false,
           :backup => false}

opt = OptionParser.new
opt.on('-f', '--rename-files') { options[:rename] = true }
opt.on('-b', '--backup')       { options[:backup] = true }

begin
  opt.parse
  # Get rid of misc args to pass the rest to ag
  args = ARGV - ["-f", "--rename-files", "-b", "--backup"]
rescue OptionParser::InvalidOption => e
  puts "Invalid option: #{e}"
  usage
end

## Perform search #################################
t = Tempfile.new('.ag-results')
out = system("ag #{args.join(' ')} --group --nocolor > #{t.path}")
puts "No matches" if out === false
if out == nil
  t.unlink
  exit 2
end

old_lines = File.open(t.path).readlines
system("#{ENV['EDITOR']} #{t.path}")
lines = File.open(t.path).readlines
t.unlink

if old_lines.length != lines.length
  puts "There was a line-number mismatch. Abort! Abort! Abort!"
  exit 3
end

## Parse edited output ############################
i = nil
current_filename = nil
lines.each_with_index do |line, i|
  line.strip!

  next if line.empty?

  if line =~ /^([0-9]+):(.+)/ # make sure it isn't actually a file
    filename = current_filename
    lineno = $1
    content = $2
  elsif line =~ /^(.+):([0-9]+):(.+)/
    if current_file
      puts "Mixing and matching groups and non-groups! Aborting."
      exit 3
    end

    filename = $1
    lineno = $2
    content = $3
  elsif File.exists?(line)
    if File.readable?(line)
      current_filename = line
    else
      puts "#{line} isn't readable. Skipping."
    end
    next
  else
    puts "Malformed line: #{line}"
    exit 3
  end

  next if line.eql?(old_lines[i].strip)

  filename = Shellwords.escape(filename)
  lineno = Shellwords.escape(lineno)
  content = content.gsub("'", "\\'")

  puts "#{filename}:#{lineno}:#{content}"

  if system("sed -i .bak '#{lineno}c\\
#{content}
  ' #{filename}")
    puts "Replaced: line #{lineno} in #{filename}"
  else
    puts "Failed to replace line #{lineno} in #{filename}"
  end

  unless options[:backup]
    system("rm -f #{filename}.bak") if File.exists?("#{filename}.bak")
  end
end

if i === nil
  puts "Didn't do nuthin'"
else
  puts "Done!"
end